With the advent of increased concern with evaporative fuel standards, there has been an increasing need for fuel lines that have increased evaporative emission requirements while at the same time, having high electrostatic discharge resistance. Further, any fuel line must likewise have economic concerns that it be amenable to high production at a low cost. A desired fuel line likewise should have appropriate physical properties of sufficient tensile strength and kink resistance, that is, the resistance of the fuel line to retaining a particular shape upon bending.
Fuel line hoses of a variety of materials have been suggested over the years. Tetrafluoroethylene has been utilized and has excellent and outstanding high temperature and chemical resistance. "Hose Technology", Publisher: Applied Science Publisher, Ltd., Essex England, by: Colin W. Evans, pages 195 through and including page 211. Nylon has also been utilized as a hose composition. The difficulties with many who have attempted to utilize fluorinated polymers is the difficulty of such materials to adhere to or have adhered to item other materials to make desirable composites.
U.S. Pat. No. 4,933,060 discloses surface modification of fluoropolymers by reactive gas plasma. The reference, however, further indicates that in order to have sufficient bonding that adhesives must be utilized prior to the application of an additional layer. Suitable adhesives are epoxys, acrylates, urethanes, and the like.
U.S. Pat. No. 4,898,638 teaches a method of manufacturing flexible gaskets which withstand chemical agents. Flexible gaskets are prepared where one film of PTFE (polytetrafluoroethylene) is directly applied onto a sheet of raw rubber and subjecting the sheet of rubber together with the film of PTFE to heating and to pressure suitable for causing the rubber to vulcanize. Use of adhesives in the bonding of fluoropolymers is likewise described in U.S. Pat. No. 4,743,327 and their use is required to make the development operative. Activating fluoropolymers utilizing ammonia gas is taught in U.S. Pat. No. 4,731,156.
None of the prior art describes a multilayered fluoropolymer with a layer of a nylon that is integral with the fluoropolymer which combined multilayered composite or pipe has desirable electrostatic discharge resistance and hydrocarbon evaporative emission resistance. Further, the prior art suggests the need for adhesives to firmly and fixedly join plastic layers. This invention does not have as an essential requirement that additional adhesives are needed in joining the fluoropolymer layer to the thermoplastic layer.
It is an object of the present invention to have a fuel pipe or tube that has a fluoropolymer substrate that is activated sufficiently to be able to have an integral top coat or layer of a thermoplastic polymer such as nylon.
It is also an object of the present invention to prepare a fluoropolymer composite by extruding a multi-layered fluoropolymer substrate, one layer of which has desirable electrostatic discharge resistance and on top of the fluoropolymer layers would be an extruded plastic layer such as a polyamide, preferably nylon.